Storage control system and method

ABSTRACT

A first storage control system comprises a CHN connected to a LAN CN. The CHN comprises a NAS processor and I/O processor. The I/O processor judges whether all or a portion of block level data is to be stored in either a first storage control system or a second storage control system, on the basis of an I/O allocation control data which indicates which of either the first storage control system or the second storage control system the block level data is to be stored in. On the basis of the result of this judgment, the I/O processor transfers the block level data from the NAS processor, to at least one of the DKA and the CHF connected to the second storage control system.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of application Ser. No.11/582,324, filed Oct. 18, 2006; which is a continuation of applicationSer. No. 10/842,490, filed May 11, 2004, now U.S. Pat. No. 7,143,228,which claims priority from Japanese Patent Application No. 2004-61934,filed on Mar. 5, 2004, the entire disclosure of which is incorporatedherein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a storage control system and method.

2. Description of the Related Art

For example, in a database system for handling large volumes of data,such as that in a data centre, or the like, data is managed by using astorage control system constituted separately from the host computer.This storage control sub-system comprises, for example, a RAID(Redundant Array of Independent Inexpensive Disks) constituted byproviding a plurality of disk type storage devices in an array fashion.

With the advance of the information-based society, the amount of data tobe managed in databases is expanding all the time. Therefore, storagecontrol systems having higher reliability and higher capacity are beingdemanded, and novel storage control systems have been developed in orderto respond these market demands. As a method for introducing a newstorage control system into a storage system, there is, for example, amethod as disclosed in Japanese Laid-Open Patent No. (Hei) 10-508967,whereby the old storage control system is replaced completely by a newstorage control system, and the storage system is constituted entirelyby the new storage control system.

If transferring completely from an old storage control system to a newstorage control system, it is possible to use the functions andcharacteristics of the new storage control system, but it is notpossible to use the old storage control system effectively, and thecosts of introducing the new system are also increased.

SUMMARY OF THE INVENTION

Therefore, it is an object of the present invention to provide a storagecontrol system and method whereby an old storage control system can beused effectively.

Further objects of the present invention will become apparent from thefollowing description.

The storage control system according to a first aspect of the presentinvention comprises: a plurality of storage devices for storing data(for example, disk type storage devices); a storage device controlsection for controlling the storage of received data in the plurality ofstorage devices (for example, a disk adapter); a connecting sectionconnected to the storage device control section; a first channel controlsection (for example, a CHN as described hereinafter) connected to atleast one of a local area network and a first storage network externalto the storage control system and to the connecting section; a secondchannel control section (for example, a CHF as described hereinafter),for transferring data sent by the first channel control section via theconnecting section, to an external storage control system via a secondstorage network external to the storage control system; a shared memorywherein first control information (for example, messages betweenprocessors) exchanged by the first channel control section, the secondchannel control section, and the storage device control section, isstored; and a cache memory for temporarily saving data exchanged betweenthe first channel control section or the second channel control sectionand the storage device control section. The first channel controlsection comprises a second processor for receiving block level data froma first processor which converts file level data received via the localarea network into the block level data. At least one of the firstprocessor and the second processor judges whether all or a portion ofthe block level data is to be stored in either the storage controlsystem or the external storage control system, on the basis of secondcontrol information indicating whether the data is to be stored ineither the storage control system or the external storage controlsystem. The second processor transfers the block level data receivedfrom the first processor, to at least one of the storage device controlsection and the second channel control section, on the basis of theresult of the judgment.

This storage control system can be representing in more abstract termsas described below, for example.

A storage control system comprising: an allocation control data storageregion for storing allocation control data; and a processor forprocessing at least one of file level data and block level data receivedvia an external communications network; wherein the allocation controldata contains address information indicating the storage destination offile identification information contained in block level data, oraddress information contained in block level data, and address locationinformation associated with the address information; and the processorrefers to the allocation control data, identifies the address locationinformation corresponding to the address information indicating thestorage destination of the file identification information contained inthe received block level data, or the address information contained inthe received block level data, and determines whether the block leveldata converted from the file level, or the received block level data, isto be stored in either a storage device belonging to the storage controlsystem, or a storage device belonging to the second storage controlsystem.

In this case, the first storage control system may be the aforementionedstorage control system itself.

In the first embodiment of a storage control system according to thefirst aspect of the present invention, the first processor receives thefile level data from a host computer, via the external local areanetwork. The second processor transfers a portion of the block leveldata based on the file level data received from the host computer, tothe second channel control section, so as to be stored in an externalstorage region belonging to the external storage control system, on thebasis of the result of the judgment, and transfers the remaining portionof the block level data to the storage device control section, so as tobe stored in an internal storage region belonging to the plurality ofstorage devices. According to this first embodiment, block level databased on data from the host computer is stored in a storage regioncombining the external storage region and the internal storage region.

In the second embodiment of a storage control system according to thefirst aspect of the present invention, the first channel control sectionsets a storage region combining an external storage region belonging tothe external storage control system and an internal storage regionbelonging to the storage control system, as a logical unit, to be anaccess object of the host computer transmitting the file level data.

In the third embodiment of a storage control system according to thefirst aspect of the present invention, the storage control systemfurther comprises a second control information storage region in whichthe second control information is stored. The first processor isprovided in the first channel control section. At least one of the firstprocessor and the second processor judges whether all or a portion ofthe block level data is to be stored in either the storage controlsystem or the external storage control system, on the basis of thesecond control information stored in the second control informationstorage region. The second control information storage region isprovided in a cache memory, for example.

In the fourth embodiment of a storage control system according to thefirst aspect of the present invention, a plurality of addressinformation elements, and information indicating which of either thestorage control system or the external storage control system each ofthe plurality of address information elements corresponds to, arerecorded in the second control information. At least one of the firstprocessor and the second processor refers to the second controlinformation and judges which of either the storage control system or theexternal storage control system the address information contained in theblock level data corresponds to.

In the fifth embodiment of a storage control system according to thefirst aspect of the present invention, the second control informationcontains file metadata relating to files managed by the first processor.The file metadata contains a plurality of file identificationinformation elements and save destination address information elementscorresponding respectively to the plurality of files. The firstprocessor identifies the save destination address informationcorresponding to the file identification information contained in thereceived file level data, from the file metadata. At least one of thefirst processor and the second processor refers to the second controlinformation and judges which of either the storage control system or theexternal storage control system the save destination address informationthus identified corresponds to.

In the sixth embodiment of a storage control system according to thefirst aspect of the present invention, a virtual intermediate storagedevice provided between the internal storage region belonging to thestorage control system and the storage devices. The virtual intermediatestorage device associates the internal storage region with the externalstorage region belonging to the external storage control system.

The storage control method according to a second aspect of the presentinvention comprises: a converting step, a judging step, a first transferstep, a storing step and a second transfer step. In the converting step,a first processor converts file level data received via a local areanetwork, into block level data. In the judging step, at least one of thefirst processor and a second processor belonging to a first channelcontrol section connected to a communications network external to thestorage control system judges whether all or a portion of the blocklevel data is to be stored in either the storage control system or theexternal storage control system, on the basis of second controlinformation indicating which of the storage control system and theexternal storage control system the data is to be stored in. In thefirst transfer step, the second processor transfers the block level datareceived from the first processor, to at least one of a storage devicecontrol section controlling the storage of data in the plurality ofstorage devices provided by the storage control system, and a secondchannel control section connected to the external storage control systemvia a storage network. In the storing step, the storage device controlsection stores received data in at least one of the plurality of storagedevices, if data is received from the second processor. In the secondtransfer step, if data is received from the second processor, the secondchannel control section transfers the received data to the externalstorage control system.

In a first embodiment of a storage control method according to thesecond aspect of the present invention, the first processor receives thefile level data from a host computer, via the external local areanetwork. In the first transfer step, the second processor transfers aportion of the block level data based on the file level data receivedfrom the host computer, to the second channel control section, so as tobe stored in an external storage region belonging to the externalstorage control system, on the basis of the result of the judgment, andtransfers the remaining portion of the block level data to the storagedevice control section, so as to be stored in an internal storage regionbelonging to the plurality of storage devices.

In a second embodiment of a storage control method according to thesecond aspect of the present invention, a further step is provided inwhich the first channel control section sets a storage region combiningthe external storage region belonging to the external storage controlsystem and an internal storage region belonging to the storage controlsystem, as a logical unit, to be an access object of the host computertransmitting the file level data.

In a third embodiment of a storage control method according to thesecond aspect of the present invention, a further step is provided inwhich the second control information is stored in a second controlinformation storage region. The first processor is provided in the firstchannel control section. In the judging step, at least one of the firstprocessor and the second processor judges whether all or a portion ofthe block level data is to be stored in either the storage controlsystem or the external storage control system, on the basis of thesecond control information stored in the second control informationstorage region.

In a fourth embodiment of a storage control method according to thesecond aspect of the present invention, a plurality of addressinformation elements, and information indicating which of either thestorage control system or the external storage control system each ofthe plurality of address information elements corresponds to, arerecorded in the second control information. In the judging step, atleast one of the first processor and the second processor refers to thesecond control information and judges which of either the storagecontrol system or the external storage control system the addressinformation contained in the block level data corresponds to.

In a fifth embodiment of a storage control method according to the thirdaspect of the present invention, the second control information containsfile metadata relating to files managed by the first processor. The filemetadata contains a plurality of file identification informationelements and save destination address information elements correspondingrespectively to the plurality of files. The storage control methodfurther comprises a step in which the first processor identifies thesave destination address information corresponding to the fileidentification information contained in the received file level data,from the file metadata. In the judging step, at least one of the firstprocessor and the second processor refers to the second controlinformation and judges which of either the storage control system or theexternal storage control system the save destination address informationthus identified corresponds to.

In a sixth embodiment of a storage control method according to thesecond aspect of the present invention, an internal storage regionbelonging to the storage control system is associated with the externalstorage region belonging to the external storage control system, via avirtual intermediate storage device provided between the internalstorage region and the storage devices.

The storage control system according to a third aspect of the presentinvention is a storage control system which receives file level data viaa local area network, comprising: a memory for storing received filelevel data, and a processor for converting the file level data stored inthe memory, into block level data. The processor judges whether all or aportion of the block level data is to be stored in either a firststorage control system located externally to the storage control systemor a second storage control system located externally to the firststorage control system, on the basis of second control informationindicating which of either the storage control system or the externalstorage control system, the data is to be stored in, and transfers theresult of the judgment and the block level data, to the first storagecontrol system, via a storage network.

The storage control system according to the third aspect of the presentinvention may be, for example, a NAS (Network Area Storage) head, or itmay be a NAS itself.

Moreover, at least one of the first storage control system and thesecond storage control system is a RAID system, for example. Morespecifically, for example, the first storage control system comprises: aplurality of storage devices for storing data; a storage controlsub-system for transferring data received via at least one of a localarea network and storage network, external to the first storage controlsystem, to an external storage control system, via the same storagenetwork as the storage network, or a separate storage network to same;and a memory for temporarily saving data received via at least one ofthe local area network and the storage network. The storage controlsub-system comprises a separate processor for receiving block level datafrom the processor provided in the storage control system (for example,the NAS head). This separate processor transfers the block-level datareceived from the processor, to at least one of the storage devicecontrol section and the second channel control section, on the basis ofthe result of the judgment.

The storage control sub-system of the first storage control system maycomprise, for example, the processor which receives file level data viaa local area network and converts the file level data thus received intoblock level data. Moreover, in this case, for example, at least one ofthe processor and the separate processor judges whether all or a portionof the block level data is to be stored in either the first storagecontrol system or the second storage control system, on the basis ofcontrol information indicating whether the data is to be stored ineither the first storage control system or the second storage controlsystem.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a general view of the external appearance of a storagecontrol system relating to one embodiment of the present invention;

FIG. 2 is a block diagram showing the composition of a storage systemrelating to the present embodiment;

FIG. 3 is a schematic diagram showing the logical connection structurebetween the first storage control system 600 and the second storagecontrol system 40;

FIG. 4 is an illustrative diagram showing an overview of a mapping tableTm;

FIG. 5 is a block diagram showing an example of the composition of a CHN21A;

FIG. 6 is a block diagram showing an example of the composition of theCHF 21B;

FIGS. 7(A) and 7 (B) show the processing sequence relating totransmission and reception of an I/O allocation control data 820;

FIG. 8 shows the processing sequence implemented when a file I/O commandreceived from the host device 10A is converted to a block I/O commandand output;

FIG. 9 shows the example of the composition of the address managementdata 853 and file metadata 854 contained in the allocation control data820, together with the detailed processing sequence of I/O allocationprocessing carried out on the basis of that allocation control data 820;

FIGS. 10(A) and 10(B) show the processing sequence implemented when thefile metadata 854 is updated;

FIG. 11 shows a processing sequence carried out in a case where the CHF21B of the first storage control system 600 creates a mapping table Tm;

FIGS. 12(A) and 12(B) are a schematic diagram showing processing in thecase of data writing;

FIG. 13 is an illustrative diagram showing the sequence of processing inFIG. 12, in relation to the respective tables;

FIGS. 14(A) and 14(B) are a conceptual diagram of a case where data isread out from an external LDEV;

FIG. 15 shows an example of the composition of a CHN 21A relating to afirst modification example of the present embodiment;

FIG. 16 shows one example of a processing sequence relating to the firstmodification example of the present embodiment;

FIG. 17 shows an example of the composition of a CHN 21A relating to asecond modification example of the present embodiment;

FIG. 18 shows one example of a processing sequence relating to thesecond modification example of the present embodiment;

FIG. 19 is a block diagram showing the composition of a storage systemrelating to a third modification of the present embodiment;

FIG. 20 shows an example of the composition of the integrated CHF/CHNadapter 21D.

FIG. 21 is a block diagram showing the composition of a storage systemrelating to a fourth modification of the present embodiment;

FIG. 22 shows an example of the composition of a NAS head 950 and a CHA21C;

FIGS. 23(A) and 23(B) show a processing sequence according to the fourthmodification example of the present embodiment, in a case where a I/Oallocation control data 820 is exchanged; and

FIG. 24 shows an example of a processing sequence according to thefourth modification example of the present embodiment, carried out in acase there a file I/O command output by the host device 10A istransferred as a block I/O command.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

An overview of one embodiment of the present invention is now described.

In the present embodiment, the storage control system, such as a RAIDsystem, or the like, is connected to a host terminal, by means of afirst communications network (for example, a LAN) through whichfile-level data is exchanged. Moreover, the storage control system isconnected to an external storage control system via a secondcommunications network through which block-level data is exchanged (forexample, a SAN (Storage Area Network)). Both the storage control systemand the external storage control system are provided with logicalstorage devices for storing data (hereinafter, referred to as “LDEV”,being an abbreviation for “Logical Device”). The LDEVs are provided inone or a plurality of disk type storage devices. The storage controlsystem and the external storage control system are provided with a diskcontrol section for controlling the storage of data in the disk typestorage devices. The storage control system comprises a first and asecond channel control section. The first channel control sectioncomprises a first processor for receiving file-level data via the firstcommunications network and converting same into block-level data, and asecond processor for receiving block-level data from the firstprocessor. The second channel control section transfers the block-leveldata received from the first channel control section, to the externalstorage control system, via the second communications network. At leastone of the first and second processors judges whether to store all or aportion of the block-level data, in either the storage control system orthe external storage control system, on the basis of I/O (Input/Output)allocation control data which indicates which of the storage controlsystem or external storage control system the data is to be stored in.The second processor transfers the block-level data received from thefirst processor, to at least one of the disk control section and thesecond channel control section, on the basis of this judgment result.

Below, the present embodiment is described in detail with reference tothe drawings.

FIG. 1 shows a general view of the external appearance of a storagecontrol system relating to one embodiment of the present invention.

The storage control system 600 may be constituted by a base frame unit10, and a plurality of add-on frame units 12 (although it may also beconstituted by a base frame unit 11 only.).

The base frame unit 10 is the smallest composition unit of the storagecontrol system 600. Provided respectively in a detachable manner in thisbase frame unit 10 are, for example, a plurality of disk type storagedevices (for example, hard disk drives (HDD)) 300, a plurality ofcontrol packages (for example, channel control sections or displaycontrol sections) 105, a plurality of power units 400, and a pluralityof parity units 500. Furthermore, a plurality of cooling fans 13 arealso provided in the base frame unit 10.

Each add-on frame 12 is an optional storage control system 600, forexample, a maximum of four add-on frames 12 can be connected to any onebase frame unit 10. Furthermore, a plurality of cooling fans 13 are alsoprovided in each add-on frame unit 12. A plurality of disk type storagedevices 300, a plurality of power supply units 400, and a plurality ofparity units 500 are provided in a respectively detachable fashion, ineach of the add-on frame units 12, these respective elements each beingcontrolled by means of a control function of a control package 105provided in the base frame unit 10.

FIG. 2 is a block diagram showing the composition of a storage systemrelating to the present embodiment.

One or a plurality of host devices, for example, two host devices 10A,10B are respective computer devices provided with information processingresources, such as a CPU (Central Processing Unit), memory, and thelike, and they are constituted in the form of a personal computer,workstation, main frame computer, or the like. The host devices 10A, 10Brespectively comprise, for example, information input devices (notillustrated), such as keyboard switches, pointing device, microphone, orthe like, and information output devices (not illustrated), such as amonitor display, speakers, and the like, for example. Moreover, each ofthe host devices 10A, 10B is provided with, for example, an applicationprogram 11, such as database software using storage region provided by afirst storage control system 600, and adapters 12A or 12B for accessingthe first storage control system 600 via a communications network CN1.

The host device 10A is connected to the first storage control system is600 via a first communications network CN1. The communications networkCN1 is a communications network for exchanging data at file level, andaccording to circumstances, a LAN, the Internet, a dedicated circuit, apublic circuit, or the like, could be used for same (hereinafter, it issupposed that the first communications network is a “LAN”). Datacommunications via the LAN are conducted in accordance with a TCP/IP(Transmission Control Protocol/Internet Protocol), for example. The hostdevice 10A requests data input and output in file units, to the firststorage control system 600, by specifying a file name. The adapter 12Aconnected to the LAN CN1 is a network card (illustrated as “PORT”) whichis compatible with a LAN, for example.

The host device 10B is connected to the first storage control system 600via a third communications network CN3. The third communications networkCN3 is a communications network for exchanging data at block level, andis constituted by a SAN (Storage Area Network), for example,(hereinafter, it is supposed that the third communications network is a“SAN”). The host device 10B requests data input and output, to the firststorage control system 600, in units of blocks which is the datamanagement unit in the storage region provided by a plurality of diskstorage device (for example, hard disk drives), in accordance with afiber channel protocol. The adapter 12 connected to the SAN CN3 is ahost bus adapter (illustrated as “HBA”) for example.

In the diagrams, the host device 10A or 10B is connected only to thefirst storage control system 600 via the LAN CN1 or SAN CN3, but it isalso possible for at least one of the host devices 10A and 10B to beconnected to a second storage control system 40, by means of the secondcommunications network CN2. The second communications network CN2 may beconstituted, for example, by a SAN, LAN, Internet, dedicated circuit,public circuit, or the like, but in the present embodiment, it issupposed that it is constituted by a fiber channel switch (hereinafter,abbreviated to “FC-SW”).

The first storage control system 600 is, for example, a RAID systemcomprising a plurality of disk storage device arranged in an arrayfashion. The first storage control system 600 is not limited to this,and it may also be constituted by an intelligent-type fiber channelswitch providing high functionality. As described hereinafter, the firststorage control system 600 may also not be provided with a local storagedevice that it controls directly itself, since the storage resources ofthe second storage control system 40 are provided to the host devices 10as individual logical volumes (Logical Units).

The first storage control system 600 may be divided broadly into astorage control sub-system 20 and a disk unit 30. The storage controlsub-system 20 comprises, for example, a channel control section 21, adisk control section 800, an SVP (Service Processor) 23, a cache memory24, a shared memory 25 and a connecting section 26. The channel controlsection 21 comprises, for example, one or more channel adapters NAS(CHN) 21A, one or more channel adapters (CHA) 21C, and one or more fiberchannel adapters (CHF) 21B. The disk control section 800 comprises aplurality of disk adapters (DKA) 22.

The CHN 21A conducts data communications with the host device 10A. TheCHN 21A is provided with a communications port 207A for performingcommunications with the host device 10A. Moreover, the CHN 21A isconstituted, for example, by a microcomputer system comprising a CPU,memory, and the like, and it interprets and executes various commandsreceived from the host device 10A. The CHN 21A is assigned with anetwork address (for example, an IP address or WWN), for identifyingthat CHN 21A. The CHA 21N is able to receive an I/O command for a fileunit from a host device 10, via the LAN CN1, (for example, a commandcontaining a file name, and a command for reading or writing a filehaving that file name, hereinafter, referred to as a “file I/Ocommand”), and behave as a NAS (Network Attached Storage) for processingthat file I/O command. The composition and functions of the CHN 21A aredescribed in detail hereinafter.

The CHA 21C conducts data communications with the host device 10B. TheCHA 21C is provided with a communications port 207C for performingcommunications with the host device 10B. Moreover, the CHA 21C isconstituted, for example, by a microcomputer system comprising a CPU,memory, and the like, and it interprets and executes various commandsreceived from the host device 10B. The CHA 21C is assigned with anetwork address (for example, an IP address or WWN), for identifyingthat CHA 21C. The CHA 21C is able to receive I/O commands in block units(hereinafter, called “block I/O commands), from the host device 10B, viathe SAN CN3, and to process those block I/O commands. A block unit isthe management unit for data in the storage region in the disk storagedevice 400 described hereinafter.

The CHF 21B is connected via a communications port 207B to the FC-SW 2.The CHF 21B is constituted, for example, in the form of a microcomputerhaving a CPU, memory and the like, which is able to exchange data withthe second storage control system 40, by means of the FC-SW 2. Thecomposition and functions of the CHF 21B are described in detailhereinafter.

The respective DKAs 22 perform data exchange with the logical storagedevices (hereinafter, LDEVs) 31, 32 in the disk unit 30. Each DKA 22 isprovided with a communications port for connecting to the disk typestorage device 400 which provides the LDEVs 31, 32. Moreover, each DKA22 is constituted in the form of a microcomputer having a CPU, a memory,and the like. Each DKA 22 writes data received from the CHN 21A or theCHA 21C, to the LDEVs 31, 32, or transmits data read out from the LDEVs31, 32, to the CHN 21A or CHA 21C. Each DKA 22 converts the logicaladdress to a physical address, when it inputs data to or outputs datafrom the LDEVs 31, 32.

The cache memory (hereinafter, referred to also as “CM”) 24 is, forexample, a volatile or non-volatile memory, which temporarily storesdata received from the host devices 10 and data read out from the LDEVs31, 32. Moreover, the cache memory 24 is also capable of storing I/Oallocation control data 820, described hereinafter, and instead of same,or in addition to same, the I/O allocation control data 820 may also bestored in the LDEV 31.

The shared memory (hereinafter, also referred to as “SM”) 25 is, forexample, a non-volatile shared memory, which stores control informationrelating to the data exchanged with the host devices (for example,information indicating which of the cache regions reserved on the CM 24,the data is to be stored in), and the like. Moreover, the shared memory25, as well as being established as a work region (for example, a regionin which messages exchanged between the CPUs of the CHN 21A, CHA 21C,CHF 21B and DKA 22 are stored temporarily), is also used to storevarious types of data, such as a mapping table group TG, and the like.It is also possible to use any one or a plurality of the LDEVs 31, 32 asa disk for caching.

The connecting section 26 provides a mutual connection between the CHN21A, CHA 21C, CHF 21B, the respective DKAs 22, the cache memory 24 andthe shared memory 25. The connecting section 26 may be constituted by ahigh-speed bus, such as an ultra-high-speed crossbar switch, or thelike, which performs data transfer by means of a high-speed switchingoperation.

The disk unit 30 comprises a plurality of disk storage devices 400arranged in an array fashion. For the disk storage devices 400, it ispossible to use, for example, devices such a hard disk, flexible disk,magnetic tape, semiconductor memory, optical disk, or the like. TheLDEVs 31, 32 are provided in a storage region of the disk storage device400. The LDEVs 31 (or 32) is able to store I/O allocation control data,which is described hereinafter. The LDEV 32 indicated by the dotted lineindicates a state where an LDEV 42 belonging to the second storagecontrol system 40 is incorporated into the first storage control system600. In other words, an LDEV situated externally from the viewpoint ofthe first storage control system 600, (hereinafter, called “externalLDEV”) 42 is provided to the host device 10 in the form of an internalLDEV 32 of the first storage control system 600.

The SVP 23 is an information processing terminals for maintaining ormanaging the first storage control system 600 (for example, anotebook-type personal computer). The SVP 23 is connected to theprocessors (for example, the CPU) in the CHN 21A, CHA 21C, CHF 21B andthe respective DKAs 22, for example, by means of an internal LAN 410.The SVP 23 monitors the occurrence of faults in the first storagecontrol system 600, displaying same on a display screen, and is used toinstruct shut off processing, and the like, relating to the disk storagedevice 400.

The second storage control system 40 may have a similar composition ofthe first storage control system 600, or it may have a simplercomposition than the first storage control system 600. For example, thesecond storage control system 40 comprises a CHF 217 having acommunications port 41, and one or a plurality of disk storage devices401. The LDEV 42 is provided in a storage region of the disk storagedevice 401. The second storage control system 40 is connected to thefirst storage control system 600 via the FC-SW 2, in such a manner thatthe LDEV of the second storage control system 40 (in other words, theexternal LDEV) 42 is treated as an internal LDEV 32 of the first storagecontrol system 600.

At least one of the internal LDEV 31 (or the internal LDEV 32) and theCM 24 is able to store I/O allocation control data 820 used incontrolling which of the first storage control system 600 or the secondstorage control system 40 block I/O data is allocated to (for example,at the address management data 853 of the address management data 853and file metadata 854 described below). This I/O allocation control data820 (for example, address management data 853) may, for example, beinput by the SVP 23 to at least one of the CHN 21A, CHA 21C, CHF21B andthe respective DKAs 22, and this I/O allocation control data 820 may bestored in at least one of the CM 24 and the internal LDEV 31 (orinternal LDEV 32).

Above, a general description of a storage system 1 relating to thepresent embodiment was given.

FIG. 3 is a schematic view showing the logical connection structurebetween the first storage control system 600 and the second storagecontrol system 40.

As shown in this diagram, the first storage control system 600 comprisesthree storage layers, consisting of VDEVs 101, LDEVs 31, and LUNs 103,in ascending order.

The VDEV 101s are virtual devices situated in the bottommost position ofthe logical storage layers. The VDEVs 101 are virtual representations ofphysical storage resources, and can be applied to a RAID structure. Morespecifically, it is possible to form a plurality of VDEVs 101 from asingle disk storage device 400 (“slicing”), and it is also possible toform a single VDEV 101 from a plurality of disk storage devices 400(“striping”). The VDEV 101 shown on the left-hand side in FIG. 3 is avirtual representation of a disk storage device 400 according to aprescribed RAID structure, for example.

On the other hand, the VDEV 101 shown on the right-hand side in FIG. 3may be used as an internal LDEV 32 of the first storage control system600, by mapping external LDEVs 42 provided by the disk storage device401 of the second storage control system 40, to the VDEV 101, by meansof the mapping table group TG (for example, the mapping table Tm in thisgroup). In the example illustrated in this diagram, the VDEV 101 isconstituted by striping of four external LDEVs 42A-42D existingrespectively in four second storage control systems 40A-40D. Each of theexternal LDEVs 42A-42D can be accessed respectively and independentlyvia respective communications ports 41A-41D, by identifying respectiveLUNs (Logical Unit Numbers) 43A-43D. Each communications port 41A-41D isassigned with a WWN (World Wide Name), which is unique identificationinformation. Therefore, by specifying a combination of a WWN and LUN tothe FC-SW 2, the first storage control system 600 is able to view anexternal LDEV 42 belonging to the LUN contained in that combination, viathe FC-SW 2. If there are a plurality of LDEVs belonging to the LUN,then the plurality of LDEVs are provided to the host device 10, by thefirst storage control system 600, as a single logical storage device.

The mapping table group TG comprises a mapping table Tm, and a firstconversion table T1 and a second table T2 prepared on the basis of thismapping table Tm. These respective tables Tm, T1 and T2 are described indetail below.

Internal LDEVs 32 are provided above the VDEVs 101. The internal LDEVs32 are logical devices which are virtual representations of the virtualdevices (VDEVs). It is possible to connect two internal LDEVs 32 to oneVDEV 101, or to connect one internal LDEV 32 to a plurality of VDEVs101. The internal LDEVs 32 can be accessed via respective LUNs 103. Inthis way, in the present embodiment, it is possible to use externalLDEVs 42 as a single internal LDEV 32 of the first storage controlsystem 600, by connecting the externals LDEVs 42 to an intermediatestorage layer (VDEV 101 and internal LDEV 32) situated between the LUNs103 and the external LDEVs 42.

As shown in the diagram, the first storage control system 600 comprisesa mixture of internal LDEVs 32 which are connected to the external LDEVs42, and internal LDEVs 31 which are not connected to external LDEVs 42.In the example illustrated in this diagram, an internal LDEV 31 and aninternal LDEV 32 are associated with the LUN “1”. Therefore, if thefirst storage control system 600 has received an LUN specification of“1” from the host device 10A, then it is able to provide a singlelogical unit (LU) comprising the storage region of the internal LDEV 32and the storage region of the external LDEV 42 associated with thatinternal LDEV 32, as an accessible object, to the host device 10A.

FIG. 4 shows an overview of a mapping table Tm.

In the mapping table Tm, VDEV identification information for identifyingthe respective VDEVs 101 (hereinafter, referred to as “VDEV#”) andinformation relating to the external LDEVs 42 (hereinafter, referred toas “external device information”) are mutually associated. The externaldevice information contains, for example, system identificationinformation, the storage capacity of the external LDEV 42, informationindicating the device type (for instance, whether it is a tape typedevice or disk type device, or the like), and information on the path tothe external LDEV 42. The system identification information is, forexample, information containing the vendor ID, model and serial numberof the second storage control system 40. The path information may beconstituted by comprising unique identification information (WWN), and aLUN 4, for each communications port 41. The system identificationinformation and WWN, and the like, illustrated in FIG. 4 are values usedfor the sake of the description, and do not have any particular meaning.Moreover, the VDEV 101 having VDEV number “3” shown at the bottom ofFIG. 4 is associated with three path information elements. Morespecifically, the external LDEV 42 mapped to this VDEV 101 (#3) has aninternal alternative path structure comprising three paths, and it ismapped to the VDEV 101 (#3) by recognizing this alternative pathstructure. Since it is recognized that the same storage region can beaccessed by passing via any one of these three paths, then even if afault, or the like, occurs in any one or any two or the paths, it isstill possible to access the desired data by means of the remaining pathwhich is operating normally.

By adopting the mapping table Tm shown in FIG. 4, it is possible to mapone or a plurality of external LDEVs 42 to one or more internal LDEVs 32in the first storage control system 600.

FIG. 5 is a block diagram showing an example of the composition of theCHN 21A.

The CHN 21A comprises a communications port 207A, a LAN controller 503,a data transfer LSI 501, a bridge LSI 502, one or a plurality ofinput/output control sections 510 comprising an I/O processor 504 and anI/O memory 507, a memory controller 505, a NAS processor 506, a CHNmemory 508 and a connector 509.

The LAN controller 503 controls the communications port 207A inaccordance with instructions received from the NAS processor 506 via thememory controller 505 and the bridge LSI. The LAN controller 503controls transmission and reception of file I/O commands in accordancewith a TCP/IP protocol, for example.

The bridge LSI 502 is, for example, a LSI (Large-Scale Integratedcircuit) for enabling mutual communications between the LAN controller503, the memory controller 505 and the data transfer LSI 501.

The memory controller 505 is an LSI for controlling communicationsbetween the NAS processor 506 and the CHN memory 508. The memorycontroller 505 is connected to the NAS processor 506, the CHN memory 508and the bridge LSI 502.

The CHN memory 508 is able to store programs for controlling the NASprocessor 506, and data for exchange between the CM 24 and the hostdevice 10A, and the like. The CHN memory 508 is also able to store, forexample, a command analysis processing program 811, an I/O allocationprocessing program 812, a file system program 817 and a network controlprogram 818. The command analysis processing program 811, I/O allocationprocessing program 812, file system program 817 and network controlprogram 818 are able to cause prescribed processing to be executed in acomputer, such as a CPU, (for example, the NAS processor 506), by beingread into that computer. For example, the command analysis processingprogram 811 is a computer program for causing a computer to implementprocessing for analyzing a file I/O command received from the hostdevice 10A. The I/O allocation processing program 812 is a computerprogram for causing a computer to implement I/O allocation processing,described hereinafter. The file system program 817 is, for example, aprogram for managing the association between the file name contained ina file I/O command and the address information of the location at whichthe file having that file name is stored (for example, the LUN andheader logical block address), and converting the file I/O command to ablock I/O command on the basis of this association. The network controlprogram 818 is, for example, constituted by comprising two file systemprotocols, such as NFS (Network File System) and Samba. NFS accepts fileI/O commands from a host device installed with a UNIX (registeredtradename) operating system running NFS. Samba, on the other hand,accepts file I/O commands from a host terminal installed with a Windows(registered tradename) operating system running CIFS (Common InterfaceFile System).

The NAS processor 506 is a CPU or a microprocessor. The NAS processor506 is, for example, a processor of higher performance capability (forinstance, higher computational processing speed), than the I/O processor504. The NAS processor 506 is connected to the memory controller 505.The NAS processor 506 is able to read out the command analysisprocessing program 811, I/O allocation processing program 812, filesystem program 817, network control program, 818, and the like, storedin the CHN memory 508, and execute processing in accordance with thecomputer programs thus read out. The NAS processor 506, for example,accepts file I/O commands from the host device 10A, by means of thenetwork control program 818. Moreover, by means of the command analysisprocessing program 811, the NAS processor 506 analyses a file I/Ocommand received from the host device 10A and stored in the CHN memory508, to determine whether it is a read command or a write command.Furthermore, by means of the file system program 817, the NAS processor506 converts the file I/O command received from the host device 10A andstored in the CHN memory 508, into a block I/O command, which it outputsto the I/O processor 504. Furthermore, by means of the I/O allocationprocessing program 812, the NAS processor judges whether the block I/Ocommand is to be stored in an internal LDEV 31 or is to be stored in anexternal LDEV 42, and on the basis of this judgment, it is able to causethe I/O processor 504 to allocate that block I/O command to either aninternal LDEV 31 or an external LDEV 42.

The I/O processor 504 is a CPU or microprocessor, which, by means ofcomputer programs read out from the I/O memory 507, is able to performcontrol of processes, such as the exchange of data with the connectingsection 26, the exchange of commands with the I/O processors in the CHA21C or CHF 21B, and the interruption of the data communications betweenthe NAS processor 506 and the connecting section 26, and the like.Moreover, the I/O processor 504 is able to communicate with the SVP 23.

The I/O memory 507 stores a computer program, and the like, forcontrolling the I/O processor 504.

The data transfer LSI 501 is an LSI, which is connected to a connector509 in turn connected to the connecting section 26, and to the I/Oprocessor 504 and the bridge LSI, and it controls the transfer of data.

The foregoing described the composition and functions of the CHN 21A. Atleast the I/O allocation processing program 812 of the aforementionedcommand analysis processing program 811 and I/O allocation processingprogram 812 is stored in the I/O memory 507, in such a manner that theI/O processor 504 can be caused to implement I/O allocation processing.This is described in further detail below, in a modification of thepresent embodiment.

FIG. 6 is a block diagram showing an example of the composition of theCHF 21B.

The CHF 21B comprises a communications port 207B, an FC controller 602,a data transfer LSI 601, an I/O processor 603, an I/O memory 604 and aconnector 605.

The communications port 207B is a port for performing communicationswith an external device, such as the second storage control system 40.

The FC controller 602 is disposed inbetween the communications port 207Band the data transfer LSI 601. The FC controller 602 controls thetransmission and reception of block I/O commands, in accordance with afiber channel protocol, for example.

The I/O memory 604 is used to store programs for controlling the I/Oprocessor 603. The I/O memory 604 stores, for example, an externalaccess processing program 814. The external access processing program814 is a computer program for causing the computer that reads in thisprogram 814 to carry out processing for transferring a received blockI/O command to the second storage control system 60.

The I/O processor 603 is a CPU or microprocessor. The I/O processor 603is connected to the data transfer LSI 610, the I/O memory 604, and theSVP 23, and it read in various computer programs contained in the I/Omemory 604 and controls the transmission and reception of data andcommands.

The data transfer LSI 601 is an LSI, which is connected to a connector605 in turn connected to the connecting section 26, and to the I/Oprocessor 603 and FC controller 602, and it controls the transfer ofdata.

Below, the various processing sequences carried out in the presentembodiment are described.

FIG. 7 shows a processing sequence relating to the transmission andreception of the I/O allocation control data 820.

The I/O allocation control data 820 can be stored in the CHN memory 508inside the CHA 21A, by means of the processing sequence illustrated inFIG. 7(A) and FIG. 7(B), for example.

More specifically, as shown in FIG. 7(A), the NAS processor 506 outputsan instruction to the I/O processor 504, to acquire the I/O allocationcontrol data 820 (step S500).

In response to this instruction, the I/O processor 504 reads in the I/Oallocation control data 820 stored in the CM 24, to the CHN memory 508(S501). Thereby, the I/O allocation control data 820 is stored in theCHN memory 508 (S502).

More specifically, as shown in FIG. 7(B), the NAS processor 506 outputsan instruction to the I/O processor 504, to acquire the I/O allocationcontrol data 820 (step S510).

In response to this instruction, the I/O processor 504 outputs an I/Oread command for reading out the I/O allocation control data 820, to aDKA 22 which is able to access the internal LDEV 31 in which the I/Oallocation control data 820 is stored (S511).

The DKA 22 receiving the I/O read command reserves a cache region on theCM 24, acquires the I/O allocation control data 820 from the internalLDEV 31 storing the I/O allocation control data 820, and stores it inthe cache region (S512).

The I/O processor 504 reads out the I/O allocation control data 820 tothe CHN memory 508, from the reserved cache region (S513). Thereby, theI/O allocation control data 820 is stored in the CHN memory 508 (S514).

The NAS processor 506 is able to execute the I/O allocation processingdescribed hereinafter, by using the I/O allocation control data 820stored in the CHN memory 508. As shown in the diagram, for example, theI/O allocation control data 820 contains address management data 853 andfile metadata 854. The address management data 853 and file metadata 854are described hereinafter.

FIG. 8 shows the processing sequence implemented when a file I/O commandreceived from the host device 10A is converted to a block I/O commandand output.

The file I/O command output by the host device 10A is received by theCHN 21A and stored in the CHN memory 508 (S550). If the file I/O commandis a file write command, then it will contain the data file to bewritten, the file name of that file, and the LUN, for example. If thefile I/O command is a file read command, then it will contain the datafile to be read out, the file name of that file, and the LUN, forexample.

The NAS processor 506 reads out the file I/O command stored in the CHNmemory 508 (S551), and in accordance with the file analysis processingprogram 811, it analyses whether that file I/O command is a file writecommand or a file read command (S552).

Moreover, the NAS processor 506 converts the file I/O command to a blockI/O command, in accordance with the file system program 817 (S553). TheNAS processor 506 performs I/O allocation processing, describedhereinafter, on the basis of the address information contained in theconverted block I/O command, and the I/O allocation control data 820(S554).

As a result of the I/O allocation processing in S554, if external accessrequest processing is to be carried out (Y at S555), then the NASprocessor 506 outputs an external access request and the converted blockI/O command, to the I/O processor 504 (S556). In this case, the I/Oprocessor 504 transmits the received block I/O command to the I/Oprocessor 603 in the CHF 21A, by means of the connecting section 26(S557). The I/O processor 603 in the CHF 21A refers to the mapping tablegroup TG, and performs external access processing, such as convertingthe internal LUN contained in the block I/O command received from theCHN 21A to an external LUN (S558), and transferring a block I/O commandcontaining an external LUN to the CHF 217 of the second storage controlsystem 40, via the second communications network CN 2 (S559).

On the other hand, if, as a result of the I/O allocation processing inS554, if internal access request processing is to be carried out (N atS555), then the NAS processor 506 outputs an internal access request andthe converted block I/O command, to the I/O processor 504 (S560). Inthis case, the I/O processor 504 transmits the received block I/Ocommand to the DKA 22, by means of the connecting section 26 (S561).Thereby, by means of the DKA 22, the data in the block I/O command iseither written to a storage region in the internal LDEV 31 indicated bythe address information contained in the block I/O command, or data isread out from a storage region in the internal LDEV 31 indicated by theaddress information contained in the block I/O command. If data has beenread out, then the I/O processor 504 of the CHN 21A acquires the datafrom the DKA 22, via the CM 24, and transmits the data thus acquired tothe host device 10A.

In the processing sequence shown in this diagram, the external accessprocessing at S558 may be carried out by the I/O processor in the CHN21A (or the CHA 21C), instead of the I/O processor of the CHF 21B. Inthis case, the I/O processor of the CHF 21B may transfer the receivedblock I/O command to the second storage control system 40, only.

FIG. 9 shows the example of the composition of the address managementdata 853 and file metadata 854 contained in the allocation control data820, together with the detailed processing sequence of I/O allocationprocessing carried out on the basis of that allocation control data 820.

As described above, the address management table 853 and the filemetadata 854 are contained in the allocation control data 820.

The address management data 853 records a plurality of addressinformation entries, and information indicating whether each of theseaddress information entries correspond to internal or external storage.The address information may use, for example, a combination of a LUN anda header LBA (logical block address). Moreover, “internal” signifies aregion contained within the first storage control system 600, and“external” signifies a region inside the second storage control system,which is external to the first storage control system 600.

The file metadata 854 records attribute information relating to each ofthe plurality of files managed by the file system program 818 of the NASprocessor 806, for example, the file name and address informationindicating the location at which the file having that file name isstored (for example, the LUN and header LBA), as well as the data sizefor that file. Although not shown in the drawings, the file metadata 854may also contain other attribute information, such as the update timing,and the like. Moreover, the file metadata 854 may also record attributeinformation relating to a directory, rather than just files.

Below, the I/O allocation processing is described.

The I/O allocation processing program 812 read into the computer (forexample, the NAS processor 506) refers to the address management data853 and judges whether the address information contained in theconverted block I/O command (in other words, the address informationcorresponding to the file name contained in the file I/O command)corresponds to an internal or external location (S554A). Alternatively,the I/O allocation processing program 812 acquires the addressinformation corresponding to the file name contained in the file I/Ocommand, from the file metadata 854, and judges whether the acquiredaddress information corresponds to an internal or external location, byreferring to the address management data 853 (S554A).

If, as a result of the judgment in S554A, the I/O allocation processingprogram 812 identifies an external location (external at S554B), then itdetermines that an external access request is to be issued (S554C). Inthis case, the processing in S556 in FIG. 8 is carried out.

If, as a result of the judgment in S554A, the I/O allocation processingprogram 812 identifies an internal location (internal at S554B), then itdetermines that an internal access request is to be issued (S554D). Inthis case, the processing in S560 in FIG. 8 is carried out.

If, as a result of the judgment in S554A, the I/O allocation processingprogram 812 identifies both an external and an internal location (bothat S554B), then it determines that both an external access request andan internal access request are to be issued (S554D). In this case, theprocessing in both S556 and S560 in FIG. 8 is carried out. A case whereboth are identified may be, for example, a case where the range of thewrite destination or read destination address contains both addressinformation of an internal LDEV 31 which is not associated with anexternal LDEV 42, and address information of an internal LDEV 32 whichis associated with an external LDEV 42. In a concrete example, thiscorresponds to a case where data is stored in the whole storage regionhaving an LUN of “1” in FIG. 3.

In the sequence described above, I/O allocation processing is carriedout.

The contents recorded in the file metadata 854 are updated appropriatelywhen data is written to the internal LDEV 31 and internal LDEV 32 (inother words, the external LDEV 42), or data is deleted from the internalLDEV 31, 32.

FIG. 10 shows the processing sequence carried out in a case where thefile metadata 854 is updated.

The file metadata 854 can be updated by means of the processing sequenceshown in FIG. 10(A) or FIG. 10(B).

In other words, as shown in FIG. 10(A), the NAS processor 506 updatesthe file metadata 854 read out to the CHN memory 508 (S700), whenever aprescribed event has occurred, for instance, whenever data has beenwritten to the internal LDEVs 31, 32, or data has been erased from theinternal LDEVs 31, 32.

Thereupon, at a prescribed timing (for example, immediately after S700),the NAS processor 506 outputs a transfer instruction to the I/Oprocessor 504, indicating transfer of the updated file metadata 854 inthe CHN memory 508, to the CM 24 (S701).

In response to this transfer instruction, the I/O processor 504 readsout the updated file metadata 854 in the CHN memory 508 and transfers itto the CM 24 (S702). Thereby, the file metadata stored in the CM 24 isupdated by the updated file metadata 854 in the CHN memory 508.

Moreover, as shown in FIG. 10(B), the NAS processor 506 updates the filemetadata 854 read out to the CHN memory 508, similarly to S700 (S800).

Thereupon, at a prescribed timing (for example, immediately after S800),the NAS processor 506 outputs a transfer instruction to the I/Oprocessor 504, indicating transfer of the updated file metadata 854 inthe CHN memory 508, to the internal LDEV 31 (S801).

In response to this transfer instruction, the I/O processor 504 reservesa cache region on the CM 24, outputs an I/O line command to a DKA 22capable of accessing the internal LDEV 31 where the file metadata isstored (S802), and reads outs the updated file metadata 813 in the CHNmemory 508 to the reserved cache region (S803).

The DKA 22 receiving the I/O line command acquires the update filemetadata from the reserved cache region (S804), and writes the updatedfile metadata 854 thus acquired, over the file metadata in the internalLDEV 31 (S805).

Next, a case is described wherein the aforementioned mapping table Tm(see FIG. 4) is created by means of exchanging information between theCHF 21B of the first storage control system 600 (hereinafter, calledfirst CHF 21B), and the CHF 217 of the second storage control system 40(second CHF 217).

FIG. 11 shows a processing sequence carried out in a case where the CHF21B of the first storage control system 600 creates a mapping table Tm.

Although not illustrated in the diagrams, for example, the CHF 21Bissues an investigate command to the FC-SW 2, in response to which, itreceives from the FC-SW 2, the log-in requirement information requiredfor logging in to the second storage control system 40 connected to theFC-SW 2 (such as the WWN of the communications port 41 connected to theFC-SW 2, for instance). The CHF 21B registers the log in requirementinformation for each second storage control system 40 received from theFC-SW 2, in the I/O memory (in other words, a local memory) 604 or theSM 25.

If, for example, the first CHF 21B has received from the SVP 23 arequest to associate a VDEV 101 with an external LDEV 42, then thelog-in requirement information registered in the I/O memory 604 (or theSM 25) is used to log in to the second storage control system 40, viathe initiator port (207B) of the CHF 21B (S83). The second CHF 217returns a response to the log in operation from the first CHF 21B (S84),thereby completing log in.

Thereupon, the first CHF 21B transmits an inquiry command as specifiedby the SCSI (Small Computer System Interface) specifications, forexample, to the second CHF 217 (S85). The inquiry command referred tohere is used in order to clarify the type and composition of the devicesubject to the inquiry, and it allows the device issuing the inquirycommand to assess the physical structure of the device subject toinquiry.

For example, the second CHF 217 having received an inquiry commandobtains control system information relating to the second storagecontrol system 40A, from the memory (not illustrated) in the secondstorage control system 40, transmits this control system information tothe first CHF 21B (S86), and returns a prescribed response (S87). Thecontrol system information transmitted here contains, for example, thevendor ID, device name and serial number of the second storage controlsystem 40, the WWN of the communications port 41A from which the inquirycommand was received, the LUN belonging to that WWN, the LDEV numberbelonging to that LUN, and the type of disk providing that LDEV.

The first CHF 21B registers the control system information thus received(for example, system control information containing the vendor ID,device name and serial number of the second storage control system 40,the WWN, LUN and disk type), in a prescribed location of the mappingtable Tm (for example, a location corresponding to the VDEV # specifiedby the client) (S88).

Next, the first CHF 21B transmits an enquiry relating to the storagecapacity of the external LDEV 42 belonging to the LUN contained in thecontrol system information thus received (for example, a read capacitycommand based on the SCSI protocol), to the second CHF 217 (S89). Thesecond CHF 217 refers to the storage capacity information stored in thememory (not illustrated) inside the second storage control system 40,(for example, the total storage capacity of the one or more externalLDEVs 42 belonging to the LUN), and transmits the storage capacity thusfound (in other words, the storage capacity of the external LDEVs 42),back to the first CHF 21B (S90), and returns a response (S91). The firstCHF 21B registers the received storage capacity in a prescribed locationof the mapping table Tm (for example, a location corresponding to aVDEV# specified by the client) (S92).

By means of the processing described above, an association is createdbetween a VDEV# and control system information and a storage capacity.

After the VDEV# has been mapped with the external system information(information including control system information and storage capacity),then if the host device 10A carries out data input or output, to or fromthe external LDEV 42, via the first storage control system 600, thenaddress conversion, and the like, is carried by referring to the varioustables in the mapping table group TG.

Data input and output between the first storage control system 600 and asecond storage control system 40 is described with reference to FIG. 12to FIG. 14. Firstly, a case where data is written will be described onthe basis of FIG. 12 and FIG. 13. FIG. 12 is a schematic diagram showingprocessing in the case of data writing. FIG. 13 is an illustrativediagram showing the sequence of processing in FIG. 12, in relation tothe respective tables.

The CHN 21A is able to block level data obtained by converting the filelevel data from the host device 10A, to an internal LDEV 31 or 32.

If the LDEV to which the CHN 21A wishes to write data is an internalLDEV 31, then data is written in accordance with standard processing.More specifically, the data from the CHN 21A is stored provisionally inthe cache memory 24, and is then stored at a prescribed address on aprescribed disk storage device 400, from the cache memory 24 and via aDKA 22. In this case, the DKA 22 converts the logical address to aphysical address. Moreover, in the case of a RAID composition, the samedata is stored in a plurality of disk storage devices 400.

If, on the other hand, the LDEV to which the CHN 21A is seeking to writedata is an internal LDEV 32 connected to an external LDEV 42 by means ofa VDEV 102, then the data is written by means of a sequence such as thatillustrated in FIG. 12. FIG. 12( a) is a flow diagram which is centeredon illustrating the storage layers, and FIG. 12( b) is a flow diagramwhich is centered on illustrating the method in which the cache memory24 is used.

The CHN 21A states the LDEV number identifying the write destinationinternal LDEV 32, and the WWN identifying the communications port 207Afor accessing this internal LDEV 32, and issues a block unit I/O writecommand (Write) (S121). Upon receiving this I/O write command from theCHN 21A, the CHF 21B generates a block unit I/O write command fortransmission to the second storage control system 40, and it thentransmits same to the second storage control system 40 (S122). The CHF21B then generates a new write command, by changing the writedestination address information, and the like, contained in the I/Owrite command received from the CHN 21A, in order to concord with theexternal LDEV 42.

Thereupon, the CHN 21A sends the data to be written, to the CHF 21B(S123). The data received by the CHF 21B is transferred from theinternal LDEV 32, via the VDEV 101 (S124), to the external LDEV 42(S126). Here, the CHN 21A returns a writing completed response (Good) tothe host device 10, at the time that the data from the host 10A has beenstored in the cache memory 24 (S125). At the time that it receives thedata from the CHF 21B (or the time that it completes writes to theexternal LDEV 42,) the second storage control system 40 transmits awriting completed report to the CHF 21B (S127). More specifically, thetiming at which the completion of writing is reported by the CHN 21A tothe host device 10A (S125) is different to the timing at which the datais actually stored in the storage device 42 (asynchronous system).Therefore, the host device 10A is released from the data writeprocessing before the data is actually stored in the external LDEV 42,and hence it can carry out other processing.

Referring now to FIG. 12( b), a plurality of sub-blocks 24A are providedin the cache memory 24. The first storage control system 600 stores datain a prescribed location of the cache memory 24 by converting thelogical block address specified by the host device 10 to a sub-blockaddress (S124).

The procedure of converting data by means of the various tables is nowdescribed with reference to FIG. 13. As illustrated in the upper part ofFIG. 13, the CHN 21A transmits data by specifying a LUN and logicalblock address (LBA). The CHF 21B converts the data input for theinternal LDEV 32 (LUN+LBA), into data for the VDEV 101, on the basis ofthe first conversion table T1 illustrated in FIG. 13( a). The firstconversion table T1 is a LUN-LDEV-VDEV conversion table for convertingdata specifying an internal LUN 103 into data for a VDEV 101. This tableT1 is stored in the SM 25, for example, (the same applies to the tablesT2 and T2 a described hereinafter). This table T1 is constituted bymutual associations between, for example, a LUN, the number of a LDEV 32corresponding to that LUN 103 (LDEV #) and the maximum slot numberthereof, and the number of a VDEV 101 corresponding to the LDEV 102(VDEV#) and the maximum slot number thereof, and the like. Moreover,although not shown in the drawings, it is also possible for this tableT1 also to register which LBA of which LDEV 32 corresponds to whichsub-block or which slot of the cache memory 24, and the like. Byreferring to a table T1 of this kind, the CHF 21B (for example, thefirst CHF 21B) converts the data from the CHA 21A (LUN+LBA) into datafor the VDEV 101 (VDEV#+SLOT#+SUBBLOCK #).

Thereupon, the CHF 21B refers to the second conversion table T2illustrated in FIG. 13( b), and converts the data for the VDEV 101 intodata for storing by transmission to an external LUN (external LDEV 42)in the second storage control system 40. The second conversion table T2contains mutual associations between, for example, a VDEV 101 number(VDEV#), the numbers of the initiator ports for transmitting the datafrom the VDEV 101 to the second storage control system 40, the WWNs foridentifying the communications ports 41 to which data is to betransferred, and the LUNs which can be accessed via those communicationsports. On the basis of this second conversion table T2, the CHF 21Bconverts the destination information for the data to be stored, into theformat of: initiator port number #+WWN+LUN+LBA. The data comprisingchanged destination information in this way is transmitted from thedesignated initiator port, via the communications network CN2, andarrives at the designated communications port 41. Thereupon, the data isstored in a prescribed location of the external LDEV 42 which can beaccessed by means of the specified LUN 43. Since the external LDEV 42 isconstructed in a virtual manner on a plurality of disk storage devices401, the data address is converted to a physical address and the data isstored at a prescribed address on a prescribed disk.

FIG. 13( c) shows a further second conversion table T2 a. Thisconversion table T2 a is used in a case where striping or a RAIDconfiguration is used in the VDEV 101 which originates in the externalstorage device 42. The conversion table T2 a is constituted by mutualassociations between a VDEV number (VDEV#), a stripe size, a RAID level,a number for identifying a second storage control system 40 (SS#(storage system number)), an initiator port number, a WWN of acommunications port 41, and the number of a LUN 43. In the example shownin FIG. 13( c), one VDEV 101 constitutes RAID 1, by using a total offour external storage control systems identified by the SS# (1, 4, 6,7). Moreover, the three LUN assigned to SS #1 (#0, #0, #4) areestablished for the same device (LDEV #). The volume of LUN #0 isprovided with an alternative path structure having two access datapaths. In this way, in the present embodiment, it is possible to provideadditional functions, such as striping or a RAID configuration, or thelike, to the CHN 21A, by constituting a VDEV 101 from a plurality oflogical volumes (LDEVs) located externally.

The sequence of processing in a case where data is read from an externalLDEV 42 in the second storage control system 40 is now described withreference to FIG. 14.

Firstly, the CHN 21A transmits a block unit I/O read command to the CHF21B (S131). Upon receiving the I/O read command, the CHF 21B generates aseparate block unit I/O read command, in order that the required data isread out from the second storage control system 40. The CHF 21Btransmits the separately generated I/O read command to the secondstorage control system 40 (S132). In response to the separate I/O readcommand received from the CHF 21B, the second storage control system 40reads out the required data from the external LDEV 42, transmits thisdata to the CHF 21B (S133), and reports that read out has been completednormally (S135). As shown in FIG. 14( b), the CHF 21B stores the datareceived from the second storage control system 40, at a prescribedlocation in the cache memory 24 (S134).

The CHF 21B reads out the data stored in the cache memory 24, and afterperforming address conversion, it transmits the data to the CHN 21A, viathe LUN 103, and the like (S136). The CHN 21A issues a read outcompletion report (S137). In this sequence of processing for reading outdata, the conversion operation described with respect to FIG. 13 iscarried out in the reverse direction.

FIG. 14 shows a case where data is read out from the second storagecontrol system 40 in response to a request from the CHN 21A, and thisdata is stored in the cache memory 24. However, the sequence is notlimited to this, and it is also possible for all or a portion of thedata stored in the external LDEV 42 to be stored previously in the cachememory 24. In this case, the data can be read out immediately from thecache memory and transmitted to the CHN 21A, in response to a read outcommand from the CHN 21A.

According to the present embodiment described above, an I/O allocationcontrol data 820 is prepared which contains address informationcorresponding to the file name contained in the file I/O data receivedfrom the host device 10A (in other words, the address informationcontained in the block I/O data converted from the file I/O data), andinformation indicating whether this address information corresponds toan internal location or an external location. The NAS processor 806 orthe input/output processor 804 of the CHN 21A refers to this I/Oallocation control data 820 and judges whether the address informationcorresponding to the file name contained in the file I/O data receivedfrom the host device 10A relates to an internal or an external location,and the transfer destination of the block I/O data is assigned to beeither a DKA 22 in the first storage control system 600, or the CHF 21B,on the basis of this judgment result. If the CHF 21B is assigned, thenthe block I/O command is transferred by the CHF 21B to the secondstorage control system 40. Consequently, the host device 10A is able toaccess a storage region in a storage control system selected from aplurality of storage control systems, even if it outputs a file I/Ocommand, without recognizing whether the access destination is aninternal LDEV 31 of the first storage control system 600 or an externalLDEV 42 of a second storage control system 40. In other words, the firststorage control system 600 and the second storage control systems 40 areconnected and used as a single storage control system by the hostdevices 10A, 10B.

In the present embodiment described above, if the CHA 21C has receives ablock I/O command from the host device 10B, via the SAN CN3, then theinput/output processor of the CHA 21C may refer to the I/O allocationcontrol data 820, judge whether the address information contained in thereceived block I/O data corresponds to an internal or an externallocation, and assign the transfer destination for that block I/O data tobe a DKA 22 in the first storage control system 600, or the CHF 21B,depending on the judgment result.

A number of modification examples can be conceived with respect to theembodiment described above. The following descriptions will centreprincipally on the points of difference between these respectivemodification examples and the present embodiment.

(1) First Modification Example

FIG. 15 shows an example of the composition of a CHN 21A relating to afirst modification example of the present embodiment.

As shown in the diagram, in the first modification example of thepresent embodiment, a command analysis processing program 811 and an I/Oallocation processing program 812 are stored in the I/O memory 507.

FIG. 16 shows one example of a processing sequence relating to the firstmodification example of the present embodiment.

The file I/O command output by the host device 10A is received by theCHN 21A and stored in the CHN memory 508 (S950).

The NAS processor 506 outputs an instruction for reading out the fileI/O command stored in the CHN memory 508, to the I/O processor 504, andthe I/O processor 504 reads out the file I/O command, from the CHNmemory 508, in response to this instruction (S951). The I/O processor504 then performs analysis, in accordance with the file analysisprocessing program 811, to determine whether the file I/O command is afile write command or a file read command (S952), and it reports theanalysis result to the NAS processor 506 (S953).

On the basis of the analysis result thus reported, the NAS processor506, in accordance with the file system program 817, converts the fileI/O command to a block I/O command (S954) and transmits that block I/Ocommand to the I/O processor 504 (S955).

The I/O processor 504 performs the I/O allocation processing describedpreviously, on the basis of the address information contained in theconverted block I/O command, and the I/O allocation control data 820(S956).

As a result of the I/O allocation processing in S956, if external accessrequest processing is to be carried out (Y at S957), then the I/Oprocessor 504 outputs the block I/O command, to the I/O processor 504 ofthe CHF 21B (S958). In this case, the I/O processor 603 of the CHF 21Acarries out the external access processing described above (S959).

As a result of the I/O allocation processing in S956, if internal accessrequest processing is to be carried out (N at S957), then the I/Oprocessor 504 outputs the block I/O command, to a DKA 22, via theconnecting section 26 (S960).

If, as a result of the I/O allocation processing at S956, both externalaccess request processing and internal access request processing are tobe carried out, then the I/O processor 504 carries out both S958 andS960.

(2) Second Modification Example

FIG. 17 shows an example of the composition of a CHN 21A relating to asecond modification example of the present embodiment.

As shown in the diagram, in the second modification example of thepresent embodiment, a command analysis processing program 811 is storedin the CHN memory 508 and an I/O allocation processing program 812 isstored in the I/O memory 507.

FIG. 18 shows one example of a processing sequence relating to thesecond modification example of the present embodiment.

The file I/O command output by the host device 10A is received by theCHN 21A and stored in the CHN memory 508 (S151).

The NAS processor 506 reads out the file I/O command stored in the CHNmemory 508 (S152), and carries out command analysis processing inaccordance with the file analysis processing program 811 (S153). The NASprocessor 506 then converts that file I/O command to a block I/O command(S154), and transmits the block I/O command to the I/O processor 504(S155).

The I/O processor 504 performs the I/O allocation processing describedpreviously, on the basis of the address information contained in theconverted block I/O command, and the I/O allocation control data 820(S956).

The subsequent processing is the same as that in S957 to S960 in FIG. 16(S157-S160).

(3) Third Modification Example

FIG. 19 is a block diagram showing the composition of a storage systemrelating to a third modification of the present embodiment.

As this diagram illustrates, it is possible to install an integratedCHF/CHN adapter 21D which comprises an integrated CHN 21A and CHF 21B,in the first storage control system 600.

FIG. 20 shows an example of the composition of the integrated CHF/CHNadapter 21D.

The integrated CHF/CHN adapter 21D comprises a communications port 207Band an FC controller 602, in addition to the constituent elements of theCHN 21A illustrated in FIG. 5. The FC controller 602 is connected to abridge LSI 504 and a communications port 207B.

Furthermore, an external access processing program 814 as described withrespect to FIG. 6 is stored in the I/O memory 507 of the integratedCHF/CHN adapter 21D.

In the example illustrated, the I/O allocation processing program 812 isstored in the I/O memory 507, and the command analysis processingprogram 811 is stored in the CHN memory 508, but it is possible forthese programs 811, 821 to be stored in either of the memories 507, 508.

(4) Fourth Modification Example

FIG. 21 is a block diagram showing the composition of a storage systemrelating to a fourth modification of the present embodiment.

As shown in this diagram, each of a plurality of CHA 21C fitted in thefirst storage control system 600 instead of providing a CHN 21A in thefirst storage control system 600, are connected with a third storagecontrol system (for example, a NAS head, and referred to as a “NAS head”hereinafter) 950, via a fourth communications network (for example, aSAN) CN4, which is located externally to the first storage controlsystem 600. A communications port 951A connected to the LAN CN1 and acommunications ports 951B connected to the SAN CN4 are provided in theNAS head 950.

FIG. 22 shows an example of the composition of a NAS head 950 and a CHA21C.

The NAS head 950 comprises a LAN controller 1503 connected to acommunications port 951A, a bridge LSI 1502 connected to the LANcontroller 1503, a NAS memory 1508, a NAS processor 1506, a memorycontroller 1505 connected to the NAS memory 1508 and the NAS processor1506, and an FC controller 1602 connected to the bridge LSI 1502 and thecommunications port 951B. Where a respective constituent element has thesame name as a constituent element of the CHN 21A (see FIG. 5) or theCHF 21B (see FIG. 6), that element has a similar function to same. TheNAS memory 1508 has a similar function to the CHN memory 508.

The CHA 21C comprises an FC controller 711 connected to the SAN CN4 viaa communications port 207C, one or a plurality of input/output controlsections 771 having an I/O processor 119 and an I/O memory 121, a datatransfer LSI 952 connected to the FC controller 711 and the I/Oprocessor 119, and a connector 954 connected to the connecting section26 and the data transfer LSI 952 in the first storage control system600. Where a respective constituent element has the same name as aconstituent element of the CHN 21A (see FIG. 5) or the CHF 21B (see FIG.6), that element has a similar function to same.

A hub 953 is provided in the first storage control system 600. The I/Oprocessor 119 is connected via the hub 953 to the LAN CN1 and the SVP23.

In the example illustrated, the I/O allocation processing program 812 isstored in the I/O memory 121, and the command analysis processingprogram 811 is stored in the NAS memory 1508, but it is possible forthese programs 811, 812 to be stored in either of the memories 121,1508.

As the foregoing description reveals, in this fourth modificationexample, the NAS processor 506 of the CHN 21A is installed on a NAS head950 located externally to the first storage control system 600, as a NASprocessor 1506. Therefore, provided that similar communications to thecommunications carried out between the NAS processor 506 and the I/Oprocessor 504 are conducted between this NAS processor 1506 and the I/Oprocessor 119 installed in the CHA 21C, then it is possible to achievesimilar results to those of the embodiment and the first and secondmodification examples described above. Below, an example is described.

FIG. 23 shows a processing sequence according to the fourth modificationexample of the present embodiment, in a case where I/O allocationcontrol data 820 is exchanged.

For example, as shown in FIG. 23(A), the NAS processor 1506 of the NAShead 950 outputs an instruction for the acquisition of the I/Oallocation control data 820, to the I/O processor 119 of the CHA 21C,via the LAN CN1 (S300).

In response to this instruction, the I/O processor 119 of the CHA 21Creads out the I/O allocation control data 820 stored in the CM 24, andstores same in the I/O memory 121 (S301, S302). The I/O processor 119 ofthe CHA 21C transfers the I/O allocation control data 820 in the I/Omemory 121, via the LAN CN1, to the NAS head 950 (S303). Thereby, theI/O allocation is control data 820 is stored in the NAS memory 1508 ofthe NAS head 950 (S304).

Furthermore, for example, as shown in FIG. 7(B), the NAS processor 1506of the NAS head 950 outputs an instruction for the acquisition of theI/O allocation control data 820, to the I/O processor 119 of the CHA21C, via the LAN CN1 (S310).

In response to this instruction, the I/O processor 119 outputs an I/Oread command for reading out the I/O allocation control data 820, to aDKA 22 which is able to access the internal LDEV 31 in which the I/Oallocation control data 820 is stored (S311).

The DKA 22 receiving the I/O read command reserves a cache region on theCM 24, acquires the I/O allocation control data 820 from the internalLDEV 31 storing the I/O allocation control data 820, and stores it inthe cache region (S312).

The I/O processor 119 reads out the I/O allocation control data 820,from the reserved cache region, to the I/O memory 121 (S313). Thereby,the I/O allocation control data 820 is stored in the I/O memory 121(S314).

The I/O processor 119 then transfers the I/O allocation control data 820in the I/O memory 121 to the NAS head 950, via the SAN CN4, as readobject data read out in response to the acquisition instruction in S310(S315). Thereby, the I/O allocation control data 820 is stored in theNAS memory 1508 of the NAS head 950 (S316).

FIG. 24 shows an example of a processing sequence according to thefourth modification example of the present embodiment, carried out in acase there a file I/O command output by the host device 10A istransferred as a block I/O command.

A file I/O command output from the host device 10A is received by theNAS head 950, via the LAN CN1, and stored in the NAS memory 1508 (S451).

The NAS processor 1506 reads out the file I/O command stored in the NASmemory 1508 (S452), and carries out command analysis processing inaccordance with the file analysis processing program 811 (S453). The NASprocessor 1506 converts this file I/O command to a block I/O command(S454), and transmits this block I/O command to the I/O processor 119 ofthe CHA 21C, via the SAN CN4 (S455).

The I/O processor 119 carries out the I/O allocation processingdescribed above, on the basis of the address information contained inthe block I/O command thus received, and the I/O allocation control data820 (S456).

The subsequent processing is the same as that in S957 to S960 in FIG. 16(S457-S460).

The foregoing description related to the exchange between the NASprocessor 1506 of the NAS head 950 and the I/O processor 119 of the CHA21C, taking an example wherein the I/O allocation processing program 812is stored in the I/O memory 121 and the command analysis processingprogram 811 is stored in the NAS memory 1508. However, as describedabove, provided that similar communications to the communicationscarried out between the NAS processor 506 and the I/O processor 504 areconducted between the NAS processor 1506 and the I/O processor 119, thenit is possible to achieve similar results to those of the embodiment andthe first and second modification examples described above. In otherwords, if, in FIG. 7, FIG. 8, FIG. 10, FIG. 16 and FIG. 18, the CHNmemory 508 were substituted with a NAS memory 1508, the NAS processor506 were substituted with a NAS processor 1506, and the I/O processor504 were substituted with an I/O processor 119, then it would bepossible to achieve similar results to those of the embodiment and thefirst and second modification examples described above, in the fourthmodification example. Moreover, in FIG. 12 and FIG. 14, it is alsopossible to substitute the CHN 21A with the CHA 21C.

Above, an embodiment and modifications of the present invention weredescribed, but these are simply examples for the purpose of describingthe present invention and the scope of the present invention is notlimited to this embodiment and these modifications alone. The presentinvention may be implemented in various further modes. For example, inthe embodiment and respective modification examples described above, thecommunications between the first storage control system 600 and thesecond storage control system 40 may also be carried out in accordancewith an iSCSI protocol. In this case, for example, instead of the CHF inthe first storage control system 600 and the second storage controlsystem 40, it is possible to provide channel adapter iSCSI deviceshaving communications ports assigned with iSCSI names (unique ID iniSCSI protocol). Moreover, in this case, for example, in the embodimentand respective modification examples described above, it is alsopossible to exchange iSCSI names between the first storage controlsystem 600 and the second storage control system 40, instead of WWN.

1. A storage control system, comprising: a first channel control sectionconnected to a storage area network located externally to said storagecontrol system; a second channel control section for transferring data,sent from said first channel control section, to an external storagecontrol system; and a cache memory for temporarily storing data receivedvia said first channel control section or said second channel controlsection, wherein said first channel control section comprises: a secondprocessor for receiving block level data from a first processor whichconverts file level data into said block level data, wherein at leastone of said first processor and said second processor judges whether allor a portion of said block level data is to be stored in said externalstorage control system based on metadata relating to files managed bysaid first processor, wherein said second processor transfers said blocklevel data, received from said first processor, to said second channelcontrol section, based on a result of said judgment, and wherein saidmetadata contains file identification information and save destinationaddress information corresponding to a plurality of files and said firstprocessor identifies save destination address information correspondingto file identification information contained in received file level datafrom said metadata.
 2. The storage control system according to claim 1,wherein said first processor receives said file level data from a hostcomputer, and wherein said second processor transfers a portion of saidblock level data, based on the file level data received from said hostcomputer, to said second channel control section, so as to be stored inan external storage region belonging to said external storage controlsystem, based on a result of said judgment, and transfers the remainingportion of said block level data to the storage control system, so as tobe stored in an internal storage region belonging to said storagecontrol system.
 3. The storage control system according to claim 1,wherein said first channel control section sets a storage regioncombining an external storage region belonging to said external storagecontrol system and an internal storage region belonging to said storagecontrol system, as a logical unit, to be an access object of a hostcomputer transmitting said file level data.
 4. The storage controlsystem according to claim 1, further comprising: a metadata storageregion in which said metadata is stored, wherein said first processor isprovided in said first channel control section; and at least one of saidfirst processor and said second processor judges whether all or aportion of said block level data is to be stored in either said storagecontrol system or said external storage control system, based on saidmetadata stored in said metadata storage region.
 5. The storage controlsystem according to claim 1, wherein a plurality of address informationelements, and information indicating which of either said storagecontrol system or said external storage control system each of saidplurality of address information elements corresponds to, are recordedin said metadata; and at least one of said first processor and saidsecond processor refers to said metadata and judges which of either saidstorage control system or said external storage control system theaddress information contained in said block level data corresponds to.6. The storage control system according to claim 1, further comprising:a virtual intermediate storage device provided between an internalstorage region belonging to said storage control system and a pluralityof storage devices, wherein said virtual intermediate storage deviceassociates said internal storage region with an external storage regionbelonging to said external storage control system.
 7. A methodimplemented in a storage control system which includes a first channelcontrol section connected to a storage area network located externallyto said storage control system, a second channel control section fortransferring data, sent from said first channel control section, to anexternal storage control system, and a cache memory for temporarilystoring data received via said first channel control section or saidsecond channel control section, said method comprising the steps of:converting, by a first processor, file level data received by thestorage control system into block level data; receiving, by a secondprocessor, the block level data from said first processor, judging, byat least one of said first processor and said second processor, whetherall or a portion of said block level data is to be stored in saidexternal storage control system based on metadata relating to filesmanaged by said first processor, transfer, by said second processor,said block level data received from said first processor to said secondchannel control section, based on a result of said judgment, whereinsaid metadata contains file identification information and savedestination address information corresponding to a plurality of filesand said first processor identifies save destination address informationcorresponding to file identification information contained in receivedfile level data from said metadata.
 8. The method according to claim 7,further comprising the steps of: receiving, by said first processor,said file level data from a host computer via said storage area network;transferring, by said second processor, a portion of said block leveldata based on the file level data received from a host computer, to saidsecond channel control section, so as to be stored in an externalstorage region belonging to said external storage control system, basedon a result of said judgment; and transferring, by said secondprocessor, a remaining portion of said block level data to said storagecontrol system so as to be stored in an internal storage regionbelonging to said storage control system.
 9. The method according toclaim 7, further comprising the step of: setting, by said first channelcontrol section, a storage region combining an external storage regionbelonging to said external storage control system and an internalstorage region belonging to said storage control system, as a logicalunit, to be an access object of a host computer transmitting said filelevel data.
 10. The method according to claim 7, further comprising thesteps of: storing said metadata in a metadata storage region, whereinsaid first processor is provided in said first channel control section;and in said judging step, judging, by at least one of said firstprocessor and said second processor, whether all or a portion of saidblock level data is to be stored in either said storage control systemor said external storage control system based on said metadata stored ina metadata storage region.
 11. The method according to claim 7, whereina plurality of address information elements, and information indicatingwhich of either said storage control system or said external storagecontrol system each of said plurality of address information elementscorresponds to, are recorded in said metadata; and in said judging step,referring, by at least one of said first processor and said secondprocessor, to said metadata and judging which of either said storagecontrol system or said external storage control system the addressinformation contained in said block level data corresponds to.
 12. Themethod according to claim 7, further comprising the step of: associatingan internal storage region belonging to said storage control system isassociated with an external storage region belonging to said externalstorage control system, via a virtual intermediate storage deviceprovided between said internal storage region and a plurality of storagedevices.